A lot of people, including myself, undertake frugality after years of acquiring "stuff" along with the side effects of debt. Rewards credit cards can often be a justification for that extra appetizer at a restaurant. The behavioral pattern changes around credit cards and rewards structures for some are drastic, and for others it can be more subtle. But even a subtle shift in buying patterns could cost more than enough money to outweigh the yearly rewards. The studies on this are gut wrenching.

My thoughts are if you don't participate in active budgeting, and either do a passive budgeting solution (think pie charts and graphs) or nothing at all, credit cards are proven to behavioral alter you without any friction. I don't recommend them.

If you're a minimalist, someone who purposefully participates in frugality and actively tracks their finances via a solid budgeting scheme (YNAB comes to mind) and creates an environment of spending friction, I can say credit cards have their place.

My favorite cards are the ones that give bonuses to practical areas only. AMEX Blue Cash Everyday and Blue Cash Preferred promote groceries, gas, streaming services. All within the framework of a frugal lifestyle Blanket Rewards like Citi Double Cash are not inherently bad either.

Cards like rotating cash back, store specific cards (Amazon Prime Card, Target Red Card) or those that promote margin heavy industries like Restaurants are altering behaviors in potentially negative ways. Either through chasing the cash back into categories you don't normal shop in, to promoting store loyalty in such a way that it costs you better deals elsewhere.